Method for reducing fruit cracking of satsuma oranges

Abstract

The invention discloses a management method for preventing and controlling fruit cracking of Satsuma oranges, which comprises the following steps: after the beginning of spring, cleaning a garden once by using a Bordeaux mixture, spreading boron on the ground in a spring shoot growing period, spraying 15 ppm gibberellic acid (GA3) + 1 ppm forchlorfenuron on leaf surfaces in a second physiological fruit dropping initial period, adding 0.5% calcium and 0.02% boron, and using Tween-80 as an active agent, in the conventional disease prevention and control measures from May to July, a copper preparation is used for 1-2 times, and 5-10 ppm of GA3, 1 ppm of forchlorfenuron and 0.2% of calcium are sprayed once before and after the first ten-day period of July. Before and after the beginning of autumn, water is irrigated once every 3-5 days, and a drip irrigation or micro-spraying mode is adopted. By means of the method, fruit cracking of the satsuma oranges can be remarkably reduced, and the internal and external quality of the fruits cannot be remarkably affected.

Description

Technical Field

[0001] The invention relates to a method for reducing fruit cracking of Wenzhou mandarin oranges and application thereof, belonging to the technical field of fruit tree cultivation. Background Art

[0002] Wenzhou mandarin [Citrus reticulata ' Unshiu As one of the main fresh-eating wide-skinned citrus varieties in my country and even in the world, the fruit peel will crack during the rapid expansion period or even the color change period, which is called fruit cracking. Fruit cracking is a physiological disease in the citrus production process that seriously affects the production efficiency. For example, the fruit cracking rate of navel oranges can reach 15%, the fruit cracking rate of mixed citrus varieties such as Ganping can reach 70%, and the natural fruit cracking rate of Wenzhou mandarin is about 10%. However, the long-term extensive management of orchards has caused great changes in the orchard ecology. In addition, there have been more abnormal weather in recent years, resulting in a trend of increasingly serious fruit cracking of Wenzhou mandarin fruits. The fruit cracking rate in some orchards exceeds 60%.

[0003] The essence of fruit cracking is a physiological disorder in the development of the fruit and a physical process of mechanical fracture of the peel. The internal cause of fruit cracking is mainly due to the uncoordinated growth of the flesh and peel, the increased growth stress inside the flesh, and the peel's inability to resist the increased stress. The occurrence of citrus fruit cracking is a gradual rather than an explosive process. First, the division of peel cells stops earlier than that of the flesh, around late May to late June. This period varies significantly due to different varieties and planting environments. Then the white layer of the peel, the mesocarp, is squeezed by the expansion of the flesh, and cracks appear between the cells of the white layer. As the fruit develops, the cracks continue to expand and increase, and cavities appear, resulting in a continuous decrease in the thickness and toughness of the peel. Secondly, the exocarp plays an important role in the hardness of the peel. The cuticle of the outer peel is often exposed to a large number of microcracks in July and August due to the dual effects of strong sunlight and internal turgor pressure. Rain will aggravate the existence of such cracks. The cracking of many citrus fruits often starts from the rupture of such cracks. Finally, after a long drought, heavy rains suddenly hit, the flesh expands rapidly, the peel cannot grow accordingly, and the strength of the peel cannot resist the sudden change of internal stress, resulting in the peel swelling and cracking, which often causes a large reduction in production in citrus producing areas. The cracked fruits are also called important media for other diseases and insect pests in orchards. However, citrus fruit cracking is the result of the action of comprehensive factors. In addition to being directly related to rain, variety characteristics, fruit development process, and hormone and nutrient imbalances will aggravate the occurrence of fruit cracking, especially in the old production areas of Wenzhou mandarin, where copper deficiency, boron deficiency, and excessive manganese content are very common. Therefore, the research on prevention and control measures for Wenzhou mandarin fruit cracking needs to be comprehensively considered in combination with management practices.

[0004] Previous studies on citrus fruit cracking have been extensive, either from a theoretical perspective or from a practical perspective. Few reports have combined theory with prevention and control practices, and there are currently no relatively unified and effective measures that are widely recognized. The main reasons are as follows: 1) Fruit cracking has obvious regional and citrus variety characteristics. Once a certain control method has achieved certain results in a certain area, it is difficult to achieve similar results in another area or even in another year by repeating the test; 2) Fruit cracking is significantly correlated with meteorological conditions, especially dramatic fluctuations in moisture. However, moisture management is difficult to promote and apply in practice due to the lack of theoretical parameters and facilities and equipment. 3) Current prevention and control measures for citrus fruit cracking will basically cause problems such as thickening of the peel, decrease in total acid and soluble solids, and delayed chlorosis when the fruit matures, which is not conducive to the sales of high-quality fruits; 4) The application of high-concentration and high-frequency growth regulators may lead to abnormal fruit growth and even food safety issues; 5) The fruit cracking prevention and control management method is complex and incompatible with conventional management measures. It requires large input of materials and labor, and its popularization and promotion value is limited; 6) Fruit cracking prevention and control measures are independent of other nutrient or pest management measures in the orchard, resulting in such measures being only experimental and not widely applicable.

[0005] 7) There are certain differences in the characteristics of fruit cracking among different varieties of citrus, for example, transverse cracking, longitudinal cracking and internal cracking. The fruit cracking of navel oranges is mainly internal cracking near maturity, while the fruit cracking of Wenzhou mandarin oranges is mostly longitudinal cracking during the rapid expansion period of the fruit. Therefore, the prevention and control of fruit cracking needs to be targeted. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for reducing fruit cracking of Wenzhou mandarin oranges, which will not have a significant impact on the internal and external qualities of the fruit and is simple to implement. It reduces the occurrence of physiological fruit cracking from the perspective of enhancing the strength of the peel, can reduce the fruit cracking rate of the year by 10% to 20%, and significantly improve the economic benefits.

[0007] Furthermore, the Wenzhou mandarin orange can be understood in a broad sense. Wenzhou mandarin orange belongs to the category of wide-skinned citrus, native to Wenzhou City, Zhejiang Province, also known as seedless orange, can be produced early, high-yield, stable, good quality, and has a cultivation history of thousands of years. After many improvements and breeding, there are currently more than 100 varieties of Wenzhou mandarin oranges, which can be divided into three categories: extra early maturing, early maturing, and medium and late maturing. The maturity period can be from late August to December. Generally, early maturing varieties have a strong flavor and no residue, and good quality. At present, Wenzhou mandarin oranges have a certain scale of planting area in the main citrus producing areas in my country, and are also the main source of income for many farmers.

[0008] Wenzhou mandarin orange fruit cracking mainly refers to a physiological phenomenon of peel cracking that occurs during the rapid expansion period of the fruit. Due to differences in varieties and management conditions, the degree of fruit cracking also varies significantly. Generally, fruits with oval shapes, thin skins and good flavors are more likely to crack.

[0009] The technical method of the present invention to solve the above technical problems is as follows: A method for reducing fruit cracking of Wenzhou mandarin oranges, which improves fruit cracking caused by element and hormone imbalance in an orchard through timely and reasonable foliar spraying.

[0010] The beneficial result of the present invention is that the present invention is based on timely and low-concentration foliar spraying of "gibberellic acid + chlorfenapyr" with calcium, boron and copper supplementation as supplementary measures, and is supplemented by irrigation measures. The entire implementation is compatible with most conventional management measures, has low cost, strong operability, and will not have a negative effect on the fruit. At the same time, it significantly reduces the fruit cracking rate and solves the serious problem of fruit cracking in Wenzhou mandarin oranges.

[0011] A method for reducing fruit cracking of mandarin oranges comprises the following steps: 1) After harvesting, or in the spring of the following year, clean the orchard with 0.5-0.8% Bordeaux mixture once; 2) In the spring budding period (mid to late March), spread boron 5-10 g / plant on the ground. The amount to be used can be calculated using borax or commercial boron fertilizer. It can also be applied simultaneously with spring fertilization of the same year. 3) After the flowers have faded (early May), spray 0.5% calcium (Ca) and 0.03% boron (B) on the leaves, combined with the pest control spray at the time; 4) Before the second physiological fruit drop (around the end of May), spray 15-20 ppm gibberellic acid (GA3) + 1ppm chlorfenapyr + 0.5% calcium + 0.02-0.05% boron on the leaves, add Tween-80 as an active agent, and the concentration after dilution is about 0.05%, spray once; 5) In the past, when mancozeb pesticides were used more frequently to prevent and control orchard diseases, copper preparations were used to replace mancozeb pesticides in routine disease prevention and control measures before July, and the practice was repeated 1-2 times; 6) About 30-40 days after the last growth regulator spraying, during the rapid fruit expansion period, that is, the rapid accumulation period of soluble solids (late June to mid-July), use 5-10 ppm GA3 + 1ppm chlorfenapyr + 0.2% calcium. When spraying alone, add Tween-80 as an active agent. After dilution, the concentration is about 0.05%, and spray once; 7) If the temperature remains high and rainfall is low from July to August, water should be irrigated every 3-5 days around the beginning of autumn (early August). Each irrigation should ensure that the soil layer below 25 cm is fully irrigated, or when the soil moisture below 25 cm reaches 40%, you can stop irrigation. It should be carried out before the ground temperature rises rapidly in the morning (8 o'clock) and after 16 o'clock in the afternoon. Use drip irrigation or micro-spraying to complete it within 2-3 days, and avoid using flooding irrigation.

[0012] Further, in step 1), the specific steps are: after harvesting the fruits, or in combination with spring pruning, use Bordeaux mixture, which is prepared by 0.5-0.8 kg of copper sulfate, 1-1.6 kg of lime, and 100 kg of water. You can also use 400-600 times of commercial preparation 80% essential (Bordeaux mixture) wettable powder, which can be sprayed on the ground and above the ground.

[0013] The beneficial effects of adopting the above further technical solution are: using Bordeaux mixture in combination with other orchard cleaning measures can greatly reduce the base number of pests and diseases in the orchard, and supplement the calcium and copper elements that are lacking in the trees.

[0014] Furthermore, in step 2), the boron selected is borax or a higher concentration of boron fertilizer, which has a high utilization rate. Depending on the size of the tree crown, a maximum of 15 g can be used per plant. Combined with ground application in spring fertilization, avoid foliar spraying because the new shoots have not yet unfolded their leaves during this period and cannot be used efficiently.

[0015] The beneficial effects of adopting the above further technical solution are: Boron (B) is an important element that affects citrus fruit cracking. It is difficult to absorb and utilize, so it needs to be supplemented before flowering. At this time, the new roots are growing, the root system is active, and the absorption rate of B spread into the soil is high. However, excessive concentration of boron will also cause poisoning, and the amount of B used needs to be strictly controlled.

[0016] Furthermore, in step 3), the time selected is when the spring shoots have unfolded their leaves but have not yet completely leathered, and the calcium and boron used are easily absorbable preparations, such as EDTA-Ca and sugar alcohol boron, and a spreading agent (active agent) is added and sprayed on the leaves.

[0017] The beneficial effects of adopting the above further technical solution are: supplementing calcium and boron elements. At this time, the leaves have a strong absorption capacity for the trace elements sprayed on the surface, and a lower concentration can be used to achieve the effect of supplementing nutrients, avoiding a certain degree of waste.

[0018] Furthermore, in step 4), the concentrations of calcium and boron used can be appropriately increased or decreased according to the actual conditions of the orchard, and the concentration of gibberellic acid used can be appropriately increased according to the strain of Wenzhou mandarin oranges, generally not exceeding 25 ppm.

[0019] The beneficial effects of adopting the above further technical solution are: regulating the growth and development of the peel and fruit, and further supplementing calcium and boron. During this period, the peel cell division is at the end, and the peel thickness is about to reach a peak. Giving an appropriate concentration of growth regulator can improve the toughness of the peel and avoid the rapid development of intercellular microgaps caused by the stress of the flesh. Growth regulators should not be used excessively or too early, otherwise it will cause the peel to thicken significantly and even change the fruit shape of the variety.

[0020] Furthermore, in step 5), the copper preparations include Cu(OH)2, copper oxychloride or thiophanate-methyl, etc. Organic copper preparations are preferred. Generally, they can be used once, and the use time should avoid the period when red spider mites are prone to occur (around April).

[0021] The beneficial effect of adopting the above further technical solution is: preventing and controlling diseases while achieving the purpose of supplementing copper. In recent years, due to the frequent appearance of a large number of systemic and protective agents, the use of related copper preparations has been significantly reduced, and copper deficiency has also occurred in orchards, and copper deficiency may aggravate citrus fruit cracking.

[0022] Furthermore, in step 6), the second spraying of the growth regulator is carried out 30-40 days after the last spraying of the growth regulator, or 15-20 days before the onset of fruit cracking. The concentration used is adjusted according to different Wenzhou mandarin orange varieties. For particularly early-maturing varieties with mild fruit cracking, spraying is not required.

[0023] The beneficial effect of adopting the above further technical solution is that on the basis of the previous steps, the peel strength is significantly improved. At this time, the fruit is in a rapid expansion period, and the peel thickness and strength change significantly. The concentration of gibberellin and Ca used is strictly controlled, otherwise it will not only have a negative impact on the internal and external quality of the fruit, but also aggravate fruit cracking.

[0024] Furthermore, in step 7), for orchards with irrigation facilities, if the temperature continues to be high and the rainfall is low in July, and the shallow soil (10cm) humidity is ≤10%, irrigation measures should be taken in time. If the temperature is still high and the rainfall is low in August, irrigation should be carried out in accordance with the standards of slow irrigation and intermittent irrigation. Natural grass growth can also be implemented as an alternative measure to maintain soil moisture, which requires manual removal of weeds that grow vigorously in summer, and weeding again in late September.

[0025] The beneficial effect of adopting the above further technical solution is: effectively alleviating the citrus fruit cracking caused by the drastic fluctuation of tree water content and the short-term rapid water absorption of the fruit. Long-term high temperature and little rain followed by sudden rainfall is one of the main causes of citrus fruit cracking, but frequent irrigation or flooding is not conducive to preventing and controlling fruit cracking, and moderate drought stress from July to September helps to increase the soluble solids content of the fruit. Therefore, irrigation is usually not recommended in July, and the principle of slow-intermittent irrigation can be followed from early August.

[0026] The method for reducing fruit cracking of Wenzhou mandarin oranges disclosed by the present invention has an entire operation process that is basically compatible with conventional orchard management measures, does not require excessive investment of time and labor, has low cost, and is highly operable.

[0027] The method for reducing fruit cracking of Wenzhou mandarin oranges described in the present invention can be used to prevent and control fruit cracking of different Wenzhou mandarin orange varieties, and can reduce the fruit cracking rate by 10% to 25% in the year of implementation. It is based on the mechanism of fruit growth and development, focuses on the selection of prevention and control agents, spraying time and concentration, and is more scientific.

[0028] Compared with the prior art, the method for reducing fruit cracking of Wenzhou mandarin oranges disclosed in the present invention also has the following advantages: 1) The growth regulator used in the present invention is mainly gibberellic acid + chlorfenapyr, and focuses on the use time. The use concentration is low, the number of times is small, and the safe period is long. It will not cause fruit quality problems such as reduced sugar and acid, delayed chlorosis, and will not bring potential food safety problems; 2) The present invention mainly reduces the occurrence of fruit cracking by improving the strength of the fruit peel so that it can buffer the internal turgor pressure of the fruit during the peak period of fruit cracking, and will not cause deformed fruits. DETAILED DESCRIPTION

[0029] The principles and features of the present invention are described below in conjunction with specific examples. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention, and are not intended to limit the scope of the present invention. Example 1

[0030] In 2024, at the citrus production base of Taizhou Yumanyuan Fruit Professional Cooperative in Yongquan Town, Linhai City, Zhejiang Province, the target was the early-maturing Miyagawa Wenzhou mandarin orange grafted on the 20-year-old Citrus aurantium rootstock. On March 5, 0.8% equal-volume Bordeaux mixture was sprayed throughout the garden. On March 15, combined with spring compound fertilizer, 30 g of Borax (15%) granules were spread per tree. On May 7, the whole garden was sprayed for pest and disease control, adding EDTA-calcium and sugar alcohol boron (100g / L), with spray concentrations of 0.5% and 0.03% respectively. On June 2, 10 ppm gibberellic acid (75%), 1 ppm chlorfenuron (0.1%), 0.5% EDTA-calcium, 0.03% boric acid (100 g / L) and 0.05% Tween-80 were sprayed on the leaves. On July 10, the orchard was sprayed with 600 times Cu (OH) 2 (77%) as a fungicide, and 10 ppm GA3, 1 ppm chlorfenuron, 0.2% EDTA-calcium, 0.03% boric acid (100 g / L) and 0.05% Tween-80 were used at the same time. The soil moisture in the orchard was less than 15% for a short period of time from July to August of that year, and no special soil moisture management was carried out. On August 28, the fruit peel strength was measured using a texture analyzer at the peak of fruit cracking, which was 10.65 N, 21.52% higher than the 8.69 N of conventional management. By the end of September, the number of remaining fruits was counted and the average fruit cracking rate for that year was calculated to be about 30.2%, while the average fruit cracking rate in nearby orchards was over 45%. Example 2

[0031] In 2023, the test subjects were 8-year-old early-maturing Yura mandarin oranges, with the rootstock being Citrus aurantium. Fruit cracking occurred relatively early, but the severity was related to the climate and environment of the year. On March 8, 0.5% Bordeaux mixture was sprayed throughout the orchard. At the end of March, 10 g of borax (95%) was sprinkled on each tree. On May 5, the whole orchard was sprayed for pest and disease control, and 0.5% EDTA-calcium and 0.03% Solubor (20.5%) were sprayed at the same time. On June 1, 15 ppm gibberellic acid (75%), 1 ppm chlorpyrifos (0.1%), 0.5% EDTA-calcium, 0.03% Solubor (20.5%) and 0.05% Tween-80 were sprayed on the leaves. On July 6, 5 ppm GA3, 0.2% EDTA-calcium and 0.05% Tween-80 were sprayed. The orchard has more Yura fruits with smaller single fruit weights. The fruit peel strength of the fruits in the conventional management area was about 10.88 N during the peak fruit cracking period, and the final fruit cracking rate exceeded 30%, while the corresponding fruit peel strength in the experimental area was 12.45 N, and the average fruit cracking rate was only 16.6%. Example 3

[0032] In 2023, the test subjects were 10-year-old early-maturing Oita mandarin oranges, with the rootstock being Citrus aurantium and the interstock being Miyakawa mandarin oranges. Fruit cracking was relatively mild. On March 10, 30 g of 15% granules of Borax were applied to each tree. On May 5, the whole garden was sprayed with pest and disease control, adding calcium nitrate (25%) and boric acid alcohol (100 g / L), with spray concentrations of 0.5% and 0.03%, respectively. On May 25, 20 ppm gibberellic acid (75%), 1 ppm chlorfenapyr (0.1%), 0.5% calcium nitrate (25%), 0.03% boric acid (100 g / L) and 0.05% Tween-80 were sprayed on the leaves. On June 23, the orchard was sprayed with conventional pesticides, and 600 times Cu (OH) 2 (77%) was used as a fungicide. On July 15, 0.2% EDTA-calcium, 0.03% boric acid (100 g / L) and 0.05% Tween-80 were sprayed. The orchard was relatively dry in July and August of that year. From July 16 to August 22, humidity management was carried out with the help of micro-sprinkler irrigation facilities, starting at 6 am and ending at about 9 am, and starting at 4 pm and stopping at 6 pm, with a total of 7 irrigation managements. The fruit peel strength of the fruits in the conventional management area was about 9.69 N at the peak of fruit cracking, and the final fruit cracking rate exceeded 15%, while the corresponding fruit peel strength in the experimental area was 11.27 N, and the average fruit cracking rate was only 7.2%.

Claims

1. A method for reducing fruit cracking of Wenzhou mandarin oranges, characterized in that: The crown spray is carried out at two key time points by combining growth regulators and mineral elements; the growth regulators are gibberellic acid + chlorfenapyr, and the mineral elements are calcium, boron and copper; the two key time points are the second physiological fruit drop period and the rapid fruit expansion period The specific steps include: 1) After harvesting, or in the spring of the following year, clean the orchard with 0.5-0.8% Bordeaux mixture once; 2) In the spring budding period (mid to late March), spread boron 5-10 g / plant on the ground. The amount to be used can be calculated using borax or commercial boron fertilizer. It can also be applied simultaneously with spring fertilization of the same year. 3) After the flowers have faded (early May), spray 0.5% calcium (Ca) and 0.03% boron (B) on the leaves, combined with the pest control spray at the time; 4) Before the second physiological fruit drop (around the end of May), spray 15-20 ppm gibberellic acid (GA3) + 1ppm chlorfenapyr + 0.5% calcium + 0.02-0.05% boron on the leaves, add Tween-80 as an active agent, and the concentration after dilution is about 0.05%, spray once; 5) In the past, when mancozeb pesticides were used more frequently to prevent and control orchard diseases, copper preparations were used to replace mancozeb pesticides in routine disease prevention and control measures before July, and the practice was repeated 1-2 times; 6) About 30-40 days after the last growth regulator spraying, during the rapid fruit expansion period, that is, the rapid accumulation period of soluble solids (late June to mid-July), use 5-10 ppm GA3 + 1ppm chlorfenapyr + 0.2% calcium. When spraying alone, add Tween-80 as an active agent. After dilution, the concentration is about 0.05%, and spray once; 7) If the temperature remains high and rainfall is low from July to August, water should be irrigated every 3-5 days around the beginning of autumn (early August). Each irrigation should ensure that the soil layer below 25 cm is fully irrigated, or when the soil moisture below 25 cm reaches 40%, you can stop irrigation. It should be carried out before the ground temperature rises rapidly in the morning (8 o'clock) and after 16 o'clock in the afternoon. Use drip irrigation or micro-spraying to complete it within 2-3 days, and avoid using flooding irrigation.

2. A method for reducing fruit cracking of Satsuma mandarin oranges according to claim 1, characterized in that: The Bordeaux mixture used in step 1) can be prepared from 0.5-0.8 kg of copper sulfate, 1-1.6 kg of lime, and 100 kg of water. Alternatively, a commercial preparation of 80% essential (Bordeaux mixture) wettable powder at 400-600 times can be used.

3. A method for reducing fruit cracking of mandarin oranges according to claim 1, characterized in that: The boron used in step 2) is borax or higher concentration boron fertilizer, which has a high utilization rate. Depending on the size of the tree crown, a maximum of 15g can be used per plant, avoiding foliar spraying.

4. A method for reducing fruit cracking of Satsuma mandarin oranges according to claim 1, characterized in that: In step 3), the time selected is when the spring shoots have unfolded their leaves but have not yet completely leathered. The calcium and boron used are easily absorbable preparations, such as EDTA-Ca and sugar alcohol boron. Spraying alone is done by adding a spreader (active agent).

5. A method for reducing fruit cracking of Satsuma mandarin oranges according to claim 1, characterized in that: In step 4), the concentrations of calcium and boron can be appropriately increased or decreased according to the actual conditions of the orchard, and the concentration of gibberellic acid can be appropriately increased.

6. A method for reducing fruit cracking of Satsuma mandarin oranges according to claim 1, characterized in that: In step 5), the copper preparations include Cu(OH)2, copper oxychloride or thiophanate-methyl, etc. Organic copper preparations are preferred and generally only need to be used once. The use time should avoid the time when red spider mites are prone to occur.

7. A method for reducing fruit cracking of Satsuma mandarin oranges according to claim 1, characterized in that: In step 6), the spraying time is 30-40 days after the last growth regulator spraying, or 15-20 days before the onset of fruit cracking. The concentration is adjusted according to different Wenzhou mandarin orange varieties. For early-maturing varieties with mild fruit cracking, spraying is not required.

8. The method for reducing fruit cracking of Satsuma mandarin oranges according to claim 1, characterized in that: In step 7), if the temperature continues to be high and rainfall is low in July and the humidity of the shallow soil (10 cm) is ≤ 10%, irrigation measures should be taken in time. If the temperature is still high and rainfall is low in August, irrigation should be carried out according to the standards of slow irrigation and intermittent irrigation.

9. The method for reducing fruit cracking of Satsuma mandarin oranges according to claim 1, characterized in that: The entire operation process is basically compatible with conventional management measures and does not require more time and labor.

10. The method for reducing fruit cracking of Satsuma mandarin oranges according to claim 1, characterized in that: It can be used to reduce the fruit cracking rate of different Wenzhou mandarin orange varieties, focusing on the selection of reagents, spraying time and concentration, and is compatible with conventional management measures, and will not have a negative impact on the internal and external quality of the fruit.